Semiconductor device, method of making the same, circuit board, flexible substrate, and method of making substrate

ABSTRACT

This is a semiconductor device, a method of the same, a circuit board, and a flexible substrate that are easy to handle, enable quality assurance, and also enable batch connection of a flexible substrate to the electrodes of a semiconductor chip. A gap preservation member  16  is provided on a surface, of a flexible substrate  12 , on which connection portions  24  to electrodes  14  of a semiconductor chip  10  are disposed. The semiconductor chip  10  and the flexible substrate  12  are arranged in a state in which the gap preservation member  16  is interposed therebetween. The connection portions  24  provided on the flexible substrate 12 are connected to the electrodes  14  of the semiconductor chip  10 , and a molding material is injected to provide a stress absorption layer  26.

TECHNICAL FIELD

[0001] This invention relates to a semiconductor device, a method ofmaking the same, a circuit board, and a flexible substrate, and, inparticular, to a semiconductor device, a method of making the same, acircuit board, and a flexible substrate in which a flexible substrate isdisposed above an active surface of a semiconductor chip.

BACKGROUND OF ART

[0002] If high-density mounting of semiconductor devices is pursued,bare-chip mounting would be ideal. However, quality assurance andhandling are difficult in the bare chip state. To that end, asemiconductor device has been proposed in which a bare chip is packagedto form a package of a size that is close to the size of the bare chip,as disclosed in, for example, International Publication WO95/08856.

[0003] This semiconductor device is made as described below. A flexiblesubstrate (abbreviated to substrate) is disposed above the activesurface of a semiconductor chip. External electrodes for mounting areprovided on this flexible substrate. Leads provided on the flexiblesubstrate are then connected to electrodes of the semiconductor chipwhile being cut, and a resin in gel form is injected between thesemiconductor chip and the flexible substrate to complete thesemiconductor device.

[0004] With this semiconductor device, inspections can be done reliablyin the packaged state, it is possible to ensure product quality becausethe resin between the semiconductor chip and the flexible substratecovers the active surface of the semiconductor chip, and handling isalso easy.

[0005] However, with this technique, the leads must be cut one by oneand bonded one by one (single-point bonding). If an attempt is made tocut and connect all of the leads at the same time, the support of theflexible substrate disappears and therefore the connection positions ofthe leads and the electrodes are placed at different positions. Thismeans that the technique disclosed in the above Publication cannot beapplied to a batch connection method for all of the leads. This isinferior to batch connections (gang bonding) from the mass productionviewpoint.

[0006] In addition, since the substrate itself is flexible, variousproblems caused by flection of the substrate cannot be solved. Forexample, when the resin in gel form is injected between thesemiconductor chip and the substrate, there is a strong possibility thatthe injection will be uneven, because of this flection. In addition, theexternal electrodes are positioned on the top of the flexible substrate,so that it is not possible to fix the positions thereof absolutely, anddifficulties are likely to occur, particularly during the connection tothe external substrate.

[0007] In addition, a flexible substrate has to be held by a special jigpositioned so as to surround the semiconductor chip, and that jig mustbe prepared anew.

[0008] The present invention was devised in order to solve the abovedescribed problems and its objective is to prepare a semiconductordevice, a method of making the same, a circuit board, and a flexiblesubstrate that are easy to assure the quality and easy to handle, andare extremely reliable during fabrication.

[0009] This invention further provides a semiconductor device, a methodof making the same, a circuit board, and a flexible substrate that havesuperlative mass production capabilities and enable the use of existingfabrication devices without modification in the fabrication thereof.

DISCLOSURE OF INVENTION

[0010] A method of making a semiconductor device in accordance with thisinvention comprises:

[0011] a step of preparing a flexible substrate that has a regionoverlapping a semiconductor chip, the flexible substrate having externalelectrode formation portions where external electrodes are formed, theexternal electrode formation portions are formed within the overlappedregion;

[0012] a step of providing a gap preservation member on at least one ofa surface having electrodes of the semiconductor chip and a surface ofthe flexible substrate that is disposed facing the surface havingelectrodes of the semiconductor chip; and

[0013] a step of arranging the semiconductor chip and the flexiblesubstrate with surfaces thereof facing one another, in a state in whichthe gap preservation member is interposed therebetween, and connectingconnection portions formed on the flexible substrate to the electrodesof the semiconductor chip.

[0014] With this invention, the preparation of the above-describedflexible substrate makes it possible to provide a package that is of thesame size as the chip. In this state, a surface of a semiconductor chiphaving electrodes is arranged so as to face a surface of a flexiblesubstrate that is disposed facing that surface of the semiconductor chiphaving electrodes, in other words, a surface of the flexible substrateon a side on which connection portions to electrodes are positioned. Agap preservation member is provided on at least one of these surfaces.Since the semiconductor chip and the flexible substrate are arrangedwith the gap preservation member therebetween, a gap can be guaranteedreliably between the two components. This makes it unnecessary toprovide a jig for preserving this gap. Since this constant gap is heldbetween the two components from the step of assembling the semiconductorchip and the flexible substrate onward, unexpected electrical shortbetween the two components can be prevented. In addition, the connectionportions of the flexible substrate and the electrodes of thesemiconductor chip are connected together in a state in which the gappreservation member is interposed therebetween, so that the gappreservation member acts as a support shaft during the connection,enabling reliable connection.

[0015] The gap preservation member formed during the step of providingthe gap preservation member is preferably provided within a region thatexcludes a region corresponding to the external electrode formationportion. in other words, the gap preservation member is not provided ina part corresponding to the external electrode formation portion for theformation of external electrodes. This ensures that the externalelectrodes can move readily because they are not fixed by the gappreservation member, thus facilitating the relief of thermal stresses.

[0016] The batch connection of the connection portions and theelectrodes during this connection step is also preferable from theviewpoint of mass production. Note that the problem of flection of theflexible substrate is most likely to occur during the batch connection,but since the connection is performed in a state in which the flexiblesubstrate is held by the gap preservation member, this makes it possibleto prevent the problem of flection of the flexible substrate.

[0017] In addition, the method could further comprise a step of. forminga stress absorption layer between the semiconductor chip and theflexible substrate.

[0018] This stress absorption layer absorbs thermal stresses caused bythe difference in coefficients of thermal expansion between thesemiconductor chip and the flexible substrate, and also thermal stressescaused by the difference in coefficients of thermal expansion betweenthe semiconductor chip and an external connection substrate (a mountingsubstrate). In addition, if the stress absorption layer is formed in thestate in which the gap preservation member is interposed, the stressabsorption layer can be formed in a state in which the gap is reliablyheld, and thus the stress absorption layer can be formed easily and alsoreliably.

[0019] Stress relief is particularly effective if the stress absorptionlayer is provided in at least a region corresponding to the externalelectrode formation portion.

[0020] The gap preservation member could be Provided by printing aresin. For example, this gap preservation member could be formed byusing a screen-printing method to print a solder resist. If a printingmethod is used, an existing printing device could be adapted therefor,which is advantageous because it makes it possible to reduce the costsof fabrication.

[0021] Alternatively, the gap preservation member could be provided bythe ejection of a resin by an ink-jet method. The ink-jet method in sucha case is a method that is widely used in printers, for printing markson defective products after semiconductor chips have been inspected, forexample. In this method, a nozzle is used, and fine particles of resinejected from that nozzle are blown towards the object to be printed.Note that a resin that does not clog the head should be used with thisink-jet method. If such an ink-jet method is used. many of thepreparation steps that are required before printing (such as setting theink, squeegee, or plate) become unnecessary, enabling a furthershortening of the process than the printing method. Since the gappreservation member can be provided with no mechanical contact with theactive surface, even if it is formed on the active surface side of thesemiconductor chip, for example, this is preferable from the viewpointof security of the active surface of the semiconductor chip.

[0022] When an ink-jet method is used, it is particularly preferablethat the gap preservation member is provided only on the surface of thesemiconductor chip that has the electrodes, Positional accuracy betweenthe head and the object to be printed is usually required with anink-jet method. A semiconductor chip is particularly useful as regardspositional accuracy, because it has a rigid substrate. In addition, ifan ink-jet method is employed, it is possible to use a device that putsbad marks on a surface to indicate a defective semiconductor chip, thusenabling the adaptation of existing equipment therefor.

[0023] The stress absorption layer could be formed by injecting amolding material. Injection of a molding material makes it possible toform the stress absorption layer in a region that is enclosed by theoverlapping semiconductor chip and flexible substrate. In addition, theresin can be spread reliably between the semiconductor chip and theflexible substrate,. ensuring that there are no voids between thesurface of the semiconductor chip and the flexible substrate, preventingthe accumulation of moisture, and also preventing corrosion.

[0024] A thermosetting resin could be used as this resin.

[0025] Alternatively, an ultraviolet-setting resin could be used as thisresin.

[0026] A material having properties of absorbing stresses between thesemiconductor chip and the flexible substrate could be used as the gappreservation member, and the material also forms a stress absorptionlayer by hermetically sealing the opposing surfaces of the semiconductorchip and the flexible substrate.

[0027] In such a case, the gap preservation member is also formed as astress absorption layer by hermetically and reliably sealing the twoopposing surfaces of the semiconductor chip and the flexible substrate.

[0028] This configuration makes it possible to shorten the process,because the gap preservation member also functions as a stressabsorption layer.

[0029] Since molding materials are expensive, making their useunnecessary leads to a reduction in costs.

[0030] The gap preservation member could also have thermoplasticproperties, and the step of forming a stress absorption layer couldcomprise a step of applying heat and pressure to the gap preservationmember. Since this gap preservation member has thermoplastic properties,the application of heat thereto forms a stress absorption layer. The gappreservation member also makes it easy for the completed semiconductordevice to absorb stresses when heat is applied thereto.

[0031] During the step of applying pressure, it is preferable that theposition at which pressure is applied to the gap preservation member isgradually shifted, to perform a sequence of local pressure applications.

[0032] This gap preservation member is preferably provided only on asurface of the flexible substrate disposed towards the surface of thesemiconductor chip that has electrodes.

[0033] The step of providing the gap preservation member preferablycomprises a step of forming a wiring pattern that is provided on asemiconductor chip side of the flexible substrate, wherein a pluralityof protrusions is formed on the wiring pattern during the step offorming the wiring pattern, by etching predetermined locations.

[0034] This makes it possible to form the gap preservation member duringthe step of forming the wiring pattern, thus enabling a shortening ofthe process.

[0035] The configuration could be such that through holes are providedin the flexible substrate at positions corresponding to the protrusions,and the external electrodes are provided through the through holes on asurface opposite to the surface of the flexible substrate on which thewiring pattern is provided.

[0036] An insulating resin could be painted onto positions of theprotrusions acting as the gap preservation member corresponding at leastto the semiconductor chip.

[0037] A semiconductor device that has been made by the above describedmethod comprises:

[0038] a semiconductor chip having electrodes;

[0039] a flexible substrate disposed over and overlapping thesemiconductor chip with a predetermined gap therebetween, the flexiblesubstrate having external electrode formation portions within theoverlapping region, the flexible substrate having connection portionselectrically connected to the external electrode formation portions, theconnection portions connected to the electrodes of the semiconductorchip; and

[0040] a gap preservation member provided at a position which excludes aposition corresponding to the external electrode formation portions, thegap preservation member preserving the gap.

[0041] The active region of the semiconductor chip is preferablypositioned within the overlapping region of the flexible substrate. Thisconfiguration makes it possible to add a function of protecting theactive surface of the semiconductor chip-without increasing the numberof components, by causing the active region of the semiconductor chip tobe protected by the flexible substrate.

[0042] In addition, a stress absorption layer could be positionedbetween the semiconductor chip and the flexible substrate.

[0043] Furthermore, the stress absorption layer could be provided in aposition corresponding to the external electrode formation portion.

[0044] In particular, this gap preservation member could be formed byusing at least part of the wiring pattern of the flexible substrate.

[0045] It is particularly preferable that a plurality of protrusions areprovided in the wiring pattern, at least one of the plurality ofprotrusions forms the gap preservation member, and at least one of therest of the protrusions forms a connection portion to an electrode ofthe semiconductor chip.

[0046] External electrodes could be formed on a side of the flexiblesubstrate, the side of the flexible substrate being opposite to a sidewhere the wiring pattern is formed, the external electrodes formedcorresponding to a position where the at least one of the protrusions asthe gap preservation member is formed.

[0047] The gap preservation member could be formed of resin and alsofunction as the stress absorption layer. In such a case, the resin couldbe a thermoplastic resin.

[0048] It is possible to mount the above described semiconductor deviceon a circuit board. In other words, in a circuit board on which theabove semiconductor device is mounted, any of the above describedsemiconductor devices is electrically connected thereto by externalelectrode formation portions of the semiconductor device.

[0049] In addition, external electrodes that are formed on this externalelectrode formation portion could be connected directly to connectingportions of the circuit board.

[0050] A flexible substrate used in a semiconductor device is a flexiblesubstrate comprising:

[0051] a base portion; and

[0052] a wiring pattern provided on one surface of the base portion, thewiring pattern having a plurality of protrusions formed integrallythereon, the base portion having through holes formed therein, each ofthe through holes corresponding to a position at which each of theplurality of protrusions are provided.

[0053] The plurality of protrusions preferably form connection portionsto electrodes of the semiconductor chip and also a gap preservationmember and an insulating layer is preferably provided on a surface ofthe protrusions corresponding to the gap preservation member.

[0054] Alternatively, the flexible substrate could comprise:

[0055] connection portions, the connection portions connected toelectrodes of a semiconductor chip; and

[0056] a gap preservation member made of resin, the gap preservationmember provided on a side where the connection portions are provided,the gap preservation member provided at a position that excludes theconnection portions. The gap preservation member could be made from athermoplastic resin.

BRIEF DESCRIPTION OF DRAWINGS

[0057]FIG. 1 is a cross-sectional view of a semiconductor device inaccordance with a first embodiment,

[0058]FIG. 2 is a cross-sectional view of a semiconductor device inaccordance with a second embodiment,

[0059]FIG. 3 is a cross-sectional view of a semiconductor device inaccordance with a third embodiment,

[0060]FIG. 4 is a cross-sectional view of a method of making asemiconductor device in accordance with a fourth embodiment,

[0061]FIG. 5 is a cross-sectional view of a semiconductor device inaccordance with a fifth embodiment,

[0062]FIGS. 6A and 6B are a plan view and a cross-sectional view of asemiconductor device in accordance with a sixth embodiment,

[0063]FIG. 7 is a cross-sectional view of a semiconductor device inaccordance with a seventh embodiment,

[0064]FIG. 8 is a cross-sectional view of a semiconductor device inaccordance with an eighth embodiment,

[0065]FIGS. 9A to 9C are views showing steps in the process of making asemiconductor device in accordance with a ninth embodiment,

[0066]FIG. 10 is a cross-sectional view of a semiconductor device inaccordance with a tenth embodiment, and

[0067]FIG. 11 shows a circuit board on which a semiconductor device madein accordance with any one of the first to tenth embodiments is mounted.

BEST MODE FOR CARRYING OUT THE INVENTION

[0068] Preferred embodiments of this invention are described below withreference to the drawings.

[0069] (First Embodiment)

[0070]FIG. 1 is a cross-sectional view through a semiconductor device inaccordance with a first embodiment of this invention. This semiconductordevice is covered with a flexible substrate 12 on a surface side, thatis, an active surface side, of a semiconductor chip 10. Therefore, theplan-view size of the package is substantially close to the chip size.

[0071] The semiconductor chip 10 is of a peripheral type wherein aplurality of electrodes 14 are provided around four peripheral edgeportions of a rectangular active surface 10 a. Note that the endportions of the electrodes 14 are drawn in this figure as matching theend portions of the semiconductor chip 10, but in practice the endportions of the electrodes 14 would be disposed at positions that areslightly retracted from the end portions of the electrodes 14. However,there would be no problem on packaging the semiconductor chip on whichis disposed electrodes as shown in this figure. It should be noted thatthis embodiment could equally well be applied to a semiconductor chip inwhich the electrodes are provided on only one, two, or three of theedges of the active surface.

[0072] A gap preservation member 16 is disposed above the active surface10 a. The gap preservation member 16 is formed of a material such assolder resist, but it could also be formed of a thermosetting orultraviolet-setting resin. The gap preservation member 16 could beformed of another material, irrespective of its adhesiveness, providedit has the property of maintaining a consistent shape after bonding,even if external energy (such as heat or pressure) is applied theretoduring the bonding. The height of the gap preservation member 16 ispreferably as tall as possible, from the viewpoint of a structurecapable of relieving the stresses between the substrate to be mountedand the semiconductor chip 10. However, if the height is too great, theexternal dimensions of the completed semiconductor device will naturallyincrease. In addition, some form of contrivance may necessary for thisgap. If it is necessary to inject resin or the like between thesemiconductor chip 10 and the flexible substrate 12 in order to protectthe outer surface of the semiconductor chip 10 or provide stress relief(details will be given later), for example, the height of the gappreservation member 16 is preferably within the range of about 10 to 30μm, more preferably within the range of 20 to 30 μm, to ensure that thisinjection is not obstructed and also to obtain a gap of a certaindegree.

[0073] The flexible substrate 12 is attached on the gap preservationmember 16. Since the flexible substrate 12 is designed to have a wiringpattern of approximately 5 to 35 μm thick on a thin-film base portion(generally of a thickness of approximately 25 to 125 μm), it bendseasily into a wavy shape, so it easily curls. In this embodiment, thepresence of the gap preservation member 16 between the semiconductorchip 10 and the flexible substrate 12 makes it possible to attach theflexible substrate 12 without its bending- It also ensures that auniform gap is formed between the flexible substrate 12 andsemiconductor chip 10, while ensuring that the flexible substrate 12does not bend. The gap preservation member 16 keeps a predeterminedspace between the active surface 10 a and the flexible substrate 12, andsupports the flexible substrate 12.

[0074] In this respect, the technique disclosed in InternationalPublication WO95/08856 relates to the attachment of a flexible substrateduring the bonding to the leads. There is no gap preservation member 16in that case, so it is difficult to form a uniform gap and thus it isnot possible to attach the flexible substrate 12 without it bending.This means that a region is formed between the flexible substrate andthe semiconductor chip where it is not possible to inject resin. Inaddition, this shifts the flexible substrate, causing the externalelectrodes to be shifted.

[0075] In this embodiment, the intervention of the gap preservationmember 16 makes it possible to attach the flexible substrate 12 at thecorrect position, without its bending. This also makes it possible to dobatch-bonding of a plurality of leads 20. Note that it is sufficient toprovide the gap preservation member 16 only at a position where theflexible substrate 12 might bend, from the point of view of preventingit from bending.

[0076] The provision of the gap preservation member 16 in the center ofthe flexible substrate 12, makes it easy to inject a molding material,to form a stress absorption layer 26 and/or protect the active surfaceof the semiconductor chip. Alternatively, It the gap preservation member16 is provided at an end portion of the flexible substrate 12, thatwould increase the effect of preventing bending in the flexiblesubstrate 12. There are therefore no limits on the position of the gappreservation member 16, provided that a gap is formed between theflexible substrate 12 and the active surface 10 a of the semiconductorchip. It should be noted, however, that if stress relief is to beconsidered, it is preferable that the gap preservation member 16 avoidsthe region directly below the external electrodes 22. This ensures thatthe stress absorption layer 26 is formed below the external electrode22, which is effective for absorbing thermal stresses. It is alsopreferable that the gap preservation member 16 is provided over as smalla region as possible, to ensure that a wide stress absorption layer 26is formed. Note that the region in which the gap preservation member 16is provided is determined from factors such as the ease of flection ofthe flexible substrate 12. For example, if the flexible substrate 12 isthin and easy to bend, the gap preservation member 16 could avoid onlythe regions directly under the external electrodes 22 and could beprovided over the entire remainder of the active surface of thesemiconductor chip.

[0077] The flexible substrate 12 is either slightly smaller than theactive surface 10 a of the semiconductor chip 10 when mounted, or it isof the same shape. The flexible substrate 12 is designed to have awiring pattern 18 on a base portion 13, with the wiring patternprotruding from the outer periphery of the base portion 13. Note thatthe portions of the wiring pattern 18 that protrude from the outerperiphery of the base portion are called the leads 20. The externalelectrodes 22 are provided on the wiring pattern 18. Note that alocation on the wiring pattern 18 where the external electrodes 22 areprovided is called an external electrode formation portion. Note alsothat with this embodiment a region that is slightly wider than the widthof the wiring pattern is ensured as this external electrode formationportion, to be used as lands. These external electrodes in this case areprovided within a range that does not exceed the semiconductor chip 10,in other words, they lie within the area of the semiconductor chip. Atleast one of these external electrodes is provided within this area; atmost all of the external electrodes are provided within this area. Inthis example, solder in ball or paste form is used as the externalelectrodes 22. Note that, in addition to forming the external electrodesof solder alone, a material that improves the height accuracy thereofcould be used. For example, a conductive material such as copper,silver, gold, or the like that maintains its shape at the meltingtemperature of solder, in other words, a material that has a meltingtemperature greater than that of solder, could be used therefor. Toenable the connection to the external. substrate in this case, thematerial could be formed into balls with its outer peripheries coveredin solder, or the solder could be applied beforehand on the side to bemounted of the external substrate.

[0078] The leads 20 are bent and the tips of these leads are used asconnection portions 24 facing the electrodes of the semiconductor chip10. In other words, the connection portions 24 are connected to theelectrodes 14 of the semiconductor chip 10.

[0079] The stress absorption layer 26 is then formed between theflexible substrate 12 and the semiconductor chip 10. The stressabsorption layer 26 is formed by injection of a molding material. Thisformation of the stress absorption layer 26 over the outer surface ofthe active surface 10 a of the semiconductor chip 10 protects the activesurface 10 a. It can also prevent corrosion. The stress absorption layer26 also has electrical insulating properties, which makes it possible toprevent electrical conduction between the active surface loa of thesemiconductor chip 10 and the exterior. The stress absorption layer 26also has thermoplastic properties. This means that the stress absorptionlayer 26 can absorb any thermal stresses caused by the difference in thecoefficients of thermal expansion of the flexible substrate 12 and thesemiconductor chip 10.

[0080] The gap preservation member 16 and the stress absorption layer 26are formed separately in this embodiment, so the optimal materials canbe used for each of them.

[0081] If the surface area occupied by the gap preservation member 16becomes large in the gap, giving flexibility to the gap preservationmember 16 increases the reliability, the stress absorption layer 26multiplying the effect.

[0082] Note that this figure shows a structured of the semiconductorchip 10, the base portion 13 and the wiring pattern 18, seen from thesemiconductor chip side, in such a manner that the semiconductor chip 10and the base portion 13 face each other. However, the provision of amaterial having electrical insulation properties such as the gappreservation member or the stress absorption layer, as in this example,enables the base portion and the wiring pattern to be reversed. in otherwords, the semiconductor chip 10 and the wiring pattern to be providedfacing each other. Note further that in this case, through holes must beprovided in the base portion, to allow electrical conduction between thewiring pattern and the external electrodes 22.

[0083] The description now turns to the method of making the abovedescribed semiconductor device. First of all, the flexible substrate 12provided with the wiring pattern 18, the leads 20, and the externalelectrodes 22 is prepared. Note that the wiring pattern 18 and the leads20 must be already formed at this stage, but this does not mean it isabsolutely necessary that the external electrodes 22 have been formed atthis stage. The external electrodes 22 could equally well be provided ina subsequent step, such as after the connection of the flexiblesubstrate to the semiconductor chip. In this case, the leads 20 could bein a state in which they extend straight outward from the wiring pattern18, not in the curved state shown in FIG. 1. It is preferable thatsolder resist is then applied to the regions on the wiring pattern 18where the external electrodes 22 are not to be provided, to ensureelectrical insulation from the outside. This flexible substrate 12 isformed in such a manner as to have an overlapping region above theactive surface side of a semiconductor chip when it is assembledtherewith as a semiconductor device. In particular, the base portion ofthe flexible substrate is positioned in an overlapping region. Externalelectrode formation portions for the formation of external electrodesare formed above the base portion of this overlapping region. Thisconfiguration conforms to a standard called the chip size/scale package,which makes it possible to form the external electrodes within the areaof the semiconductor chip.

[0084] The gap preservation material (gap preservation member) 16 isprovided on the flexible substrate 12. More specifically, the gappreservation material 16 is provided on a surface of the flexiblesubstrate facing the surface of the semiconductor chip having theelectrodes 14, which in this figure is the surface on the opposite sideof the flexible substrate 12 from the surface on which the wiringpattern 18 is formed. In other words, the gap preservation material 16is provided on the surface on which are positioned the connectionsurfaces of the connection portions 24 of the leads 20 that connect tothe electrodes 14. The fabrication of the gap preservation material 16is done by painting or ejecting a resin by a screen-printing or ink-jetmethod. Alternatively, the gap maintenance could be provided byadhesion. Solder resist or a thermosetting or ultraviolet-setting resinis used as the resin, and, if necessary, it is exposed to heat orultraviolet rays. If the gap preservation material 16 is formed ofsolder resist, a step of forming the gap preservation material 16 can beperformed continuously before or after the step of applying the solderresist to the flexible substrate 12. This makes it possible to smooththe work. In this case, the solder resist applied to the flexiblesubstrate 12 also acts as a protective film that protects the leads 20both electrically and mechanically.

[0085] Note that the gap preservation material 16 need not be providedon the side of flexible substrate 12; it could be provided on the sideof the semiconductor chip; or it could equally well be provided on bothsides. Note also that if the gap preservation material 16 is provided onthe semiconductor chip side, it is preferable to use an ink-jet methodtherefor. This is because application by an ink-jet method makes itpossible to provide the gap preservation material 16, without requiringthe direct contact with the outer surface of the semiconductor chip, asin a printing method. An ink-jet method is also preferable from theviewpoint of ease of meeting the requirement for positional accuracy ofthe semiconductor chip. That is to say, it is necessary to accuratelyset the distance between the nozzle and the object to be printed (inthis case, the semiconductor chip) if an ink-jet method is used, so fromthis sense it is a useful method for a semiconductor chip that is formedfrom a rigid substrate. The ink-jet method is also extremelyadvantageous in reducing costs, in that it enables the use of a markingdevice which is generally used for adding markings to defectivesemiconductor chips and it makes it possible to restrain installationcosts by using ordinary techniques and devices.

[0086] During the step of forming the gap preservation material 16, thegap preservation material 16 is formed at a position that excludes theregion corresponding to the external electrodes 22.

[0087] The flexible substrate 12 is then placed on the semiconductorchip 10, with the gap preservation material 16 therebetween. Theconnection portions 24 are connected to the electrodes 14 of thesemiconductor chip 10, while the leads 20 are bent. In this case, aplurality of the leads 20 are provided on the flexible substrate 12, andall of the leads 20 are bonded to the electrodes 14 in a batch. Anordinary device is used for this bonding. Note that various methods ofbanding a plurality of leads in a batch are well known, so detaileddescription thereof is omitted. Note also that it is preferable to usebatch bonding (called “gang bonding”) from the viewpoint of massproductivity, but this does not mean that only batch bonding can beUsed; single-point bonding could also be used.

[0088] A molding material is then injected between the semiconductorchip 10 and the flexible substrate 12. More specifically, the moldingmaterial is injected into either holes (not shown in the figure) formedin the flexible substrate 12 or by using gaps between adjacent leads 20.The molding material could be in a gel form but it preferably tends tobe hardened to a certain degree. In the completed semiconductor device,this molding material forms the stress absorption layer 26. If thisstress absorption layer 26 is provided, it may be preferably provided ata position at least directly below the external electrodes 22.

[0089] In this manner, this embodiment ensures that a gap can beprovided by the gap preservation material 16 between the semiconductorchip 10 and the flexible substrate 12. This gap is for forming thestress absorption layer 26. The preparation for exclusive equipment isunnecessary to provide this gap. In addition, a plurality of leads 20can be bonded in a batch by using an ordinary device.

[0090] Note that if a gap preservation material is provided beforehandon the semiconductor chip side, as in this example, the flexiblesubstrate 12 can be used in the first embodiment shown in FIG. 1.

[0091] (Second Embodiment)

[0092]FIG. 2 is a view showing a semiconductor device in accordance witha second embodiment. The semiconductor device shown in this figure ischaracterized in having gap preservation materials 116 and 117 and astress absorption layer 126. Other components are similar to those ofthe semiconductor device of FIG. 1, so they are given the same referencenumbers and further description thereof is omitted.

[0093] The gap preservation materials 117 are provided at end portionsof the flexible substrate 12 in FIG. 2. This ensures that the endportions of the flexible substrate 12 are supported, so that the gappreservation material 116 provided at the center of the flexiblesubstrate 12 can be made smaller. Note that if the gap preservationmaterial 116 is used to the maximum, the maximum possible dispositionregion thereof is all the regions that excludes the regions directlybelow the external electrodes. Therefore, separate gap preservationmaterials 116 and 117 can be used at each location, but when they aredisposed over the maximum size of region, the parts thereof could bemade integral (connected except Parts thereof, although this is notshown in the figure). In other words, the configuration could be suchthat holes are formed at corresponding locations, that is, only atpositions that correspond to regions directly below the externalelectrodes.

[0094] This makes it possible to form the stress absorption layer 126 inthe regions directly underneath the external electrodes 22, enabling amore efficient absorption of stresses. In this embodiment, the leads 20that extend from the end portions of the flexible substrate 12 are bent,and the gap preservation materials 117 are provided at the end portionsof the flexible substrate 12. Therefore, when the leads 20 are beingbent, the resultant stresses can be taken by the gap preservationmaterials 117 and thus the step of bonding the leads 20 can be performedsatisfactorily. Note that, if external pressure will be applied to theleads 20 so as to bend them, it is better to provide the gappreservation materials 117 at the end portions of the base portion inparticular, However, if external pressure is applied to the flexiblesubstrate during bonding, for example, even if the leads 20 are not bentthereby, providing the gap preservation materials 117 ensures greaterreliability.

[0095]FIG. 2 is a view showing a method of making a semiconductor devicein accordance with the second embodiment and its making method issubstantially the same as that described in the first embodiment. Inother words, the method of making the gap preservation material ischanged slightly by the increase in regions over which the gappreservation materials are provided. There would be no problem whetherthe gap preservation materials 116 and 117 are formed together orseparately. In addition, they could be formed continuously (in aconnected state) or discontinuously at individual locations.

[0096] (Third Embodiment)

[0097]FIG. 3 is a view showing a semiconductor device in accordance witha third embodiment. The semiconductor device shown in this figure is avariant of the semiconductor device shown in FIG. 1, so the samecomponents are given the same reference numbers and further descriptionthereof is omitted.

[0098] In FIG. 3, a wiring pattern 218 is formed on an active surface 10a side of a flexible substrate 212. Through holes 212 a are formed inthe flexible substrate 212, and external electrodes 222 are formedprotruding, through the through holes 212 a, from the wiring pattern 218to its opposite side. Leads 220 protrude from end portions of theflexible substrate 212. These leads 220 are bent at a gentler angle thanthe leads 20 of FIG. 1, and are connected to the electrodes 14.

[0099] A stress absorption layer 226 is also provided in this embodimentbetween the flexible substrate 212 and the active surface 10 a in such amanner that thermal stresses are absorbed thereby. Since the wiringpattern 218 is formed on the side on which the stress absorption layer226 is provided in this embodiment, the wiring pattern 218 is protectedby the stress absorption layer 226. This makes it possible to omit thestep of forming a protective film for the wiring pattern 218. Note thatthe positions at which the gap preservation material is provided couldcorrespond to any of the positions described with reference to the otherembodiments.

[0100] The fabrication method thereof is substantially the same as thatdescribed with reference to the first embodiment. This fabricationmethod differs from that of the first embodiment in that a flexiblesubstrate of a slightly different shape is prepared and the surfacethereof that faces the semiconductor chip is disposed opposite to thedirection shown in FIG. 1.

[0101] (Fourth Embodiment)

[0102]FIG. 4 is a cross-sectional view of a method of making asemiconductor device in accordance with a fourth embodiment. Thesemiconductor chip 30 used in this embodiment is similar to thesemiconductor chip 10 of FIG. 1 and has electrodes 32. In thisembodiment, gap preservation materials 34 are provided beforehand on anactive surface 30 a of the semiconductor chip 30. In other words, resinis applied or ejected thereonto by screen-printing or an ink-jet method,to form the gap preservation materials 34 on the semiconductor chip 30before the connection to the leads 220 of the flexible substrate.

[0103] A flexible substrate 36 is then placed on the semiconductor chip30, with the gap preservation materials 34 therebetween, and a stressabsorption layer (not shown in the figure) is formed by the injection ofa molding material to make the semiconductor device.

[0104] In this case, the flexible substrate 36 is provided with a wiringpattern 38 on a surface of its base portion 37 on the semiconductor chip30 side. Solder bumps 40 are then provided as external electrodes on thewiring pattern 38. The solder bumps 40 project from through holes 36 aformed in the base portion 37 to the surface opposite to the surface onthe semiconductor chip 30 side. Note that this does not mean that thesolder bumps 40 must be provided at this stage; they could equally wellbe provided at a later stage, such as after the connection of protrusion42 to the electrodes 32 has ended. The protrusions 42 are formed in thewiring pattern 38 at positions corresponding to the electrodes 32 of thesemiconductor chip 30. These protrusions 42 are formed by etching thewiring pattern 38. It should be noted, however, that it is not necessaryto insist on etching as the protrusion formation method; known methodsother than etching could be used therefor, such as the formation ofbumps by a transcribing bump method. These protrusions 42 act asconnection portions to be bonded to the electrodes 32 of thesemiconductor chip 30. In this case, the flexible substrate shown inthis figure, particularly the wiring pattern thereof, is disposed insubstantially a straight line with no bending. This ensures that noexternal stresses are exerted on the wiring pattern 38, making itpossible to design for an improvement in reliability wherein cracking orthe like is unlikely to occur.

[0105] The height of the gap preservation materials 34 is substantiallythe same as or less than the total height of the protrusions 42 and theelectrodes 32, such that the connections between the protrusions 42 andthe electrodes 32 are not impeded. The protrusions need not be providedon the wiring pattern 38 side; this case could be dealt with, formingbumps on the electrodes 32 of the semiconductor chip 30.

[0106] In this embodiment, the wiring pattern 38 is provided on thesemiconductor chip 30 side of the base portion 37. In other words, thewiring pattern 38 is provided between the base portion 37 and thesemiconductor chip 30. This ensures electrical insulation by a stressabsorption layer (not shown in the figure) formed by the gappreservation materials 34 together with a molding material (resin), evenif the wiring pattern 38 is not covered by solder resist or the like.

[0107] In this embodiment, the gap preservation materials 34 areprovided in direct contact with the semiconductor chip 30. As describedabove, the gap preservation materials 34 are provided by means such asprinting, so they adhere to the active surface 30 a. Therefore, no gapis formed between the active surface 30 a and the gap preservationmaterials 34. It the active surface 30 a is covered by the stressabsorption layer, all of the region of the active surface 30 a apartfrom the electrodes 32 can be covered by resin, so there are no regionsinto which water can collect, improving the humidity-related reliabilitythereof.

[0108] As a variation of this embodiment, the gap preservation materials34 could be provided beforehand on the flexible substrate 36. In such acase, the gap preservation materials 34 could be formed by using solderresist during a step of forming a protective film on the wiring pattern38 formed on the flexible substrate 36, such as a step of printingsolder resist thereon. In particular, the gap preservation materials 34can be formed by simply forming protrusions in the protective film ofthe wiring pattern 38, because the flexible substrate 36 of thisembodiment has a wiring pattern 38 formed on its side towards the activesurface 30 a of the semiconductor chip 30.

[0109] Note that when gap preservation materials are provided beforehandon the semiconductor chip side, as in this example, the flexiblesubstrate 12 used in the first embodiment of FIG. 1, in other words, asubstrate in which the wiring pattern is placed on the outer side, canbe used without modification.

[0110] (Fifth Embodiment)

[0111]FIG. 5 is a view showing a semiconductor device in accordance witha fifth embodiment. The semiconductor device shown in this figure hasgap preservation materials at positions that differ from those of thesemiconductor device made by the process shown in FIG. 4, but itotherwise has the same configuration, so that similar components aregiven the same reference numbers and further description thereof isomitted.

[0112] In FIG. 5, gap preservation materials 134 are provided atpositions that avoid the regions directly below the solder bumps 40.More specifically, they are provided close to the end portions of theflexible substrate 36. This configuration makes it possible to provide astress absorption layer 135 directly below the solder bumps 40. Thermalstresses applied to the solder bumps 40 can be absorbed directly belowthe solder bumps 40.

[0113] (Sixth Embodiment)

[0114]FIG. 6A is a plan view of a semiconductor device in accordancewith a sixth embodiment and FIG. 6B is a cross-sectional view takenalong the line B-B in FIG. 6A.

[0115] In this semiconductor device, a plurality of the electrodes 302is provided in a zigzag pattern at the center. of a semiconductor chip300. A wiring pattern 312 is formed on a flexible substrate 310 on aside facing an active surface 300 a of the semiconductor chip 300.Protrusions 314 to be connected to the electrodes 302 are formed in thewiring pattern 312, and also external electrodes 320 are formed througha plurality of through holes 310 a that are formed in the flexiblesubstrate 310.

[0116] In this embodiment too, a stress absorption layer 340 is providedbetween the flexible substrate 310 and the active surface 300 a, withgap preservation materials 330 therebetween. More specifically, the gappreservation materials 330 are provided to avoid the regions directlybelow the external electrodes 320, so that the stress absorption layer340 can be formed directly below the external electrodes 320. Thusthermal stresses can be efficiently absorbed. Note that this inventioncan be applied to an array type semiconductor chip in which theelectrodes are arranged in an array of a plurality of lines and aplurality of columns, in a similar manner to that of this embodiment.

[0117] (Seventh Embodiment)

[0118]FIG. 7 is a view showing a semiconductor device in accordance witha seventh embodiment. The semiconductor chip 300 shown in this figure isprovided with a plurality of electrodes 302 in a zigzag pattern on theactive surface 300 a, in a similar manner to that shown in FIGS. 6A and6B. A wiring pattern 352 is formed on a flexible substrate 350 on theside opposite to the active surface 300 a, and external electrodes 354are formed on the wiring pattern 352. Holes 350 a are formed in theflexible substrate 350 in the vicinity of the electrodes 302, with leads356 protruding into the interior of these holes 350 a. These leads 356are formed bent and are bonded to the electrodes 302.

[0119] In this embodiment too, a stress absorption layer 370 is providedbetween the flexible substrate 350 and the active surface 300 a, withgap preservation materials 360 therebetween. More specifically, the gappreservation materials 360 are provided to avoid the regions directlybelow the external electrodes 354, so that the stress absorption layer370 can be formed directly below the external electrodes 354. It ispreferable that a gap preservation material 360 is disposed on the sideof and to the end portion of a hole 350 a, as shown in FIG. 2, toimprove the bonding efficiency.

[0120] (Eighth Embodiment)

[0121]FIG. 8 is a cross-sectional view of a method of making asemiconductor device in accordance with an eighth embodiment. In thisfigure, a semiconductor device that is a completed product has asemiconductor chip 50, a flexible substrate 54, and a stress absorptionlayer 69. The semiconductor chip 50 is similar to the semiconductor chip10 of FIG. 1 and has electrodes 52.

[0122] The flexible substrate 54 has a base portion 56 and a wiringpattern 58 provided thereon. Solder bumps 64 are provided on the wiringpattern 58, in a similar manner to the embodiment of FIG. 4. Note that,in order to provide these solder bumps 64, aperture portions are formedin the base portion, and pad regions 58 a are formed by using the wiringas is. These pad regions 58 a are generally formed to be slightly largerthan the pattern width, to provide the external electrodes. The wiringpattern 58 is provided on the rear surface side of the flexiblesubstrate 54, in a manner similar to that of the embodiment of FIG. 4,so that it is not exposed to the exterior and is thus protected.

[0123] A plurality of protrusions 60 and 62 are formed in the wiringpattern 58. The protrusions 60 are used as connection portions with theelectrodes 52 of the semiconductor chip 50. More specifically, a bondingtool 68 is inserted into tool holes 56 a formed in the base portion 56,and all of the protrusions 60 are bonded to the electrodes 52 in abatch. An ordinary device could be used as this bonding tool 68. In thiscase, the flexible substrate 54, particularly the wiring pattern 58, isdisposed in substantially a straight line, without any bending, as shownin the figure. This ensures that no external stresses are exerted on thewiring pattern 58, making it possible to design for an improvement inreliability wherein cracking or the like is unlikely to occur.

[0124] The protrusions 62 are formed in the pad regions 58 a of thewiring pattern 58, on the surface thereof opposite to the solder bumps64. Since the pad regions 58 a are comparatively wide, the protrusions62 can also be formed to be large. Even so, if size is not aconsideration, the protrusions 62 could be formed at positions otherthan the pad regions 58 a. In such a case, the stress absorption layer69 could be provided directly below the solder bumps 64, so that thermalstresses can be efficiently absorbed thereby. Note that the protrusions62 could be formed integrally with the wiring pattern 58 or separatelytherefrom, in a similar manner to that described above with reference tothe previous embodiments.

[0125] Solder resist 66 is then applied over the outer surfaces of theprotrusions 62, to ensure electrical insulation from the active surface50 a. The solder resist 66 could extend slightly beyond the outersurfaces of the protrusions 62. Note that the protrusions 60 and 62 areformed by etching the outer surface of the wiring pattern 58. Therefore,when the protrusions 60 are formed as connection portions, theprotrusions 62 can be formed at the same time, without increasing thenumber of etching steps.

[0126] The provision of the protrusions 62 and the solder resist 66makes it possible to form a gap between the active surface 50 a of thesemiconductor chip 50 and the flexible substrate 54. In other words, theprotrusions 62 and the solder resist 66 functions as a gap preservationmaterial. A molding material can be injected into this gap to form thestress absorption layer 69. The total height of the protrusions 62 andthe solder resist 66 is substantially the same as or the less than thetotal height of the protrusions 60 and the electrodes 52, such that theconnections between the protrusions 60 and the electrodes 52 are notimpeded.

[0127] The method of making the above described semiconductor device isdescribed. First of all, the flexible substrate 54 having the wiringpattern 58 which has the protrusions 60 and 62 is prepared. Theprotrusions 60 and 62 could be either integral therewith or separatetherefrom, as previously mentioned. Note, however, that an insulationprocess must be performed on the outer surfaces of the protrusions 62.The flexible substrate 54 is then placed on the semiconductor chip 50,and the protrusions 60 and the electrodes 52 are bonded together. Amolding material is injected between the flexible substrate 54 and thesemiconductor chip 50 to form the stress absorption layer 69, enablingthe completion of the semiconductor device. Note that it does not matterwhether the solder bumps 64 are formed before or after the connection(bonding) of the electrodes 52 and the protrusions 60. However, if thesolder bumps are formed before the bonding, the bonding tool must beshaped to avoid the solder bumps, as shown in the figure.

[0128] This embodiment makes it unnecessary to use an exclusive jig andenables the mounting and assembly steps by ordinary assembly devices,restraining any increase in fabrication costs.

[0129] (Ninth Embodiment)

[0130]FIGS. 9A to 9C a view showing a method of making semiconductordevice in accordance with a ninth embodiment.

[0131] A semiconductor chip 70 is a conventional one having electrodes72 on an active surface 70 a thereof. A flexible substrate 74 isprovided with a wiring pattern 78 on a base portion 76 thereof. Throughholes 80 are formed in the base portion 76. The through holes 80 are forthe provision of solder bumps acting as external electrodes. Thesesolder bumps are formed in the same manner as that illustrated in FIGS.4 and 8, so further description and illustration thereof are omitted.

[0132] Protrusions 82 are formed in the wiring pattern 78 as connectionportions to the electrodes 72. These protrusions 82 are also formed byetching.

[0133] The characteristic feature of this embodiment is the provision ofan intervening layer 84 on the flexible substrate 74. Note that in thisexample the intervening layer 84 is provided on the flexible substrate74, but the intervening layer 84 could also be provided beforehand onthe semiconductor chip side.

[0134] This intervening layer 84 is provided by applying a flexibleadhesive to the wiring pattern 78 of the flexible substrate 74.Alternatively, the intervening layer 84 could be previously formed as atape that is then affixed to the wiring pattern 78. Alternatively, atape having adhesive properties on only one surface thereof could beused as the intervening layer, and the wiring pattern could be formed byvapor deposition or the like on the other surface of the tape.

[0135] The intervening layer 84 fulfills the functions of a gappreservation member and a stress absorption layer. In other words, theintervening layer 84 is of a material that preserves a gap and it isalso of a material that absorbs thermal stresses in itself. It ispreferable that as a stress absorption layer the material thereof has acomposition comprising flexibility and moreover has thermoplastic orthermosetting properties, such as a polyimide.

[0136] The intervening layer 84 is provided to avoid the vicinity of theprotrusions 82 of the wiring Pattern 78. Therefore, the interveninglayer 84 is prevented from covering up the protrusions 82. This ensuresthat bonding defects can be prevented by the intervention of theintervening layer 84 between the protrusions 82 and the electrodes 72.

[0137] The flexible substrate 74 is then placed above the active surface70 a of the semiconductor chip 70, as shown in FIG. 9A. Morespecifically, the flexible substrate 74 is disposed, Positioning theprotrusions 82 of the wiring pattern 78 an the electrodes 72. Next, theflexible substrate 74 is mounted onto the semiconductor chip 70, asshown in FIG. 9B. Pressure and heat are then applied to the interveninglayer 84 from above the flexible substrate 74 by a jig 86. Theapplication of pressure enables the intervening layer 84 to adhere tothe active surface 70 a of the semiconductor chip 70. If the interveninglayer 84 has thermoplastic properties, the application of heat improvesthe adhesion.

[0138] In this case, the jig 86 could be a tool having a contact surfacethat is formed to be flat, as already known in the art, or it could havea contact surface to the flexible substrate 74 that is curved, as shownin FIG. 9B. Therefore, when this jib 86 is pressed down in such a mannerthat it rotates, the position at which pressure is applied is graduallyshifted, to perform a sequence of local pressure applications. Thisensures that any voids between the intervening layer 84 and the activesurface 70 a are pushed outward. Removal of such voids makes it possibleto remove air bubbles and also prevents the accumulation of moisture.

[0139] Next, a bonding tool 88 is used to bond the protrusions 82 andthe electrodes 72, as shown in FIG. 9C. The configuration of thisbonding tool 88 is such that the connection portions alone can bepressed into a connected state in a batch, but other portions thereofare not touched. In this example, the cross-sectional shape of thebonding tool 88 is indented, with protruding portions of the tool 88provided along two sides thereof. Note that the protruding portions ofthis tool could be provided in accordance with the bonding positions,such as along all four sides thereof, but it is not limited thereto.

[0140] This embodiment facilitates the bonding work by first positioningthe protrusions 82 and the electrodes 72, then attaching the interveninglayer 84 to the semiconductor chip 70. If facilitation of the bondingwork is not taken into consideration, however, the sequence could besuch that the protrusions 82 and the electrodes 72 are positioned, thebonding is performed, and then the intervening layer 84 is attached tothe semiconductor chip 70.

[0141] In accordance with the thus made semiconductor device, since theintervening layer 84 fulfills the function of a stress absorption layer,it is not necessary to inject a molding material as a stress relieflayer. Note, however, that molding material could be injecteddeliberately in the vicinity of the protrusions 82 of the wiring pattern78, with the objective of protecting the connection portions, Theomission of this expensive molding material makes it Possible to reducecosts. In addition, since no molding material is injected, thepossibility of voids being created on the active surface 70 a isreduced, increasing the yield.

[0142] (Tenth Embodiment)

[0143]FIG. 10 is a view showing a semiconductor device in accordancewith a tenth embodiment. The semiconductor device shown in this figureis a variant of the semiconductor device shown in FIG. 9C, so the samecomponents are given the same reference numbers and further descriptionthereof is omitted.

[0144] In other words, intervening layers 184 that are provided on theflexible substrate 74 are only provided directly below externalelectrodes 183. The intervening layers 184 is formed of an adhesive, inthe same manner as the intervening layer 84 of FIG. 9C. Therefore, theintervening layers 184 form gaps between the flexible substrate 74 andthe active surface 70 a, connecting the two. Note, however, that sincethe intervening layers 184 are smaller than that of FIG. 9C, theadhesion thereof is lessened.

[0145] In this case, resin 185 is injected between the flexiblesubstrate 74 and the active surface 70 a. The resin 185 connects theflexible substrate 74 and the active surface 70 a and protects theactive surface 70 a from moisture. Therefore, the resin 185 need not beprovided with properties necessary for stress absorption.

[0146] In accordance with this embodiment, the intervening layers 184connect the flexible substrate 74 and the active surface 70 a, if onlyslightly, so that gaps are formed between the two components and theflexible substrate 74 can be attached to the semiconductor chip 70thereby. The flexible substrate 74 and the active surface 70 a are alsoconnected by the resin 185 and also the active surface 70 a is protectedfrom moisture thereby. Even although the regions on which theintervening layers 184 are provided are small, they can providesufficient stress absorption.

[0147]FIG. 11 shows a circuit board 100, on which a semiconductor device110 made by applying one of the above described first to tenthembodiments, is mounted

[0148] This invention is not to be taken as limited to the abovedescribed embodiments, but various modifications thereto are possible.In particular, it is preferable that the flexible substrate is formed byusing a film carrier tape. It is also preferable that a plurality ofsemiconductor devices are made integrally on this film carrier tape, toimprove handling. In such a case, the process of mounting and assemblingthe semiconductor device can be performed on an ordinary ILB (Inner LeadBonding) line that corresponds to TAB (Tape Automated Bonding)technique.

[0149] Note that if a film carrier tape is used, it may happen that thefabrication process can not prevent the flexible substrate, particularlythe base portion thereof, from being larger than the active surface ofthe semiconductor chip; because each flexible substrate, which isintegrated with one another into a film carrier tape and will beeventually cut apart from one another, requires suspension portions inthe meantime; and because usually, these suspension portions willeventually be cut away, but the accuracy of the cutting device may causedifficulties, cutting the boundary surfaces of the semiconductor chips.Note that, in such a case, the flexible substrate could be formed widerthan the width of the semiconductor chip in two facing directions out offour directions and narrower than the width of the semiconductor chip inthe other two directions, with the suspension portions provided on itswider sides, even if it is not formed larger in all directions of thesemiconductor chip.

[0150] The above embodiments were described with reference to theso-called fan-in type of semiconductor device, but this invention is notlimited thereto and it can also be applied to a fan-in/out type ofsemiconductor device wherein external. electrodes are also providedalong the outer periphery of the semiconductor chip.

[0151] In addition, since FIGS. 1 to 9C are cross-sectional views, theyshow leads disposed in two directions, but in practice the wiringpattern could be disposed in a plurality of directions.

[0152] In the above described embodiments, bumps were formed on aflexible substrate, but other well-known bump formation techniques couldbe used to provide bumps on the semiconductor chip side, such asproviding gold bumps on the chip side.

1. A method of making a semiconductor device, comprising: a step ofpreparing a flexible substrate that has a region overlapping asemiconductor chip, said flexible substrate having external electrodeformation portions where external electrodes are formed, said externalelectrode formation portions are formed within said overlapped region; astep of providing a gap preservation member on at least one of a surfacehaving electrodes of said semiconductor chip and a surface of saidflexible substrate that is disposed facing said surface havingelectrodes of said semiconductor chip; and a step of arranging saidsemiconductor chip and said flexible substrate with surfaces thereoffacing one another, in a state in which said gap preservation member isinterposed therebetween, and connecting connection portions formed onsaid flexible substrate to said electrodes of said semiconductor chip.2. The method of making a semiconductor device as defined in claim 1 ,wherein said gap preservation member formed during said step ofproviding said gap preservation member is provided within a region thatexcludes a region corresponding to said external electrode formationportions.
 3. The method of making a semiconductor device as defined inclaim 1 or claim 2 , further comprising a step of forming a stressabsorption layer between said semiconductor chip and said flexiblesubstrate.
 4. The method of making a semiconductor device as defined inclaim 3 , wherein said stress absorption layer is provided in at least aregion corresponding to said external electrode formation portions. 5.The method of making a semiconductor device as defined in claim 1 ,wherein said gap preservation member is provided by printing a resinthereon.
 6. The method of making a semiconductor device as defined inclaim 1 , wherein said gap preservation member is provided by ejecting aresin in an ink-jet method.
 7. The method of making a semiconductordevice as defined in claim 6 , wherein said gap preservation member isprovided only on said side having said electrodes of said semiconductorchip.
 8. The method of making a semiconductor device as defined in claim3 , wherein said stress absorption layer is formed by injecting amolding material.
 9. The method of making a semiconductor device asdefined in any one of claims 5 to 7 , wherein said resin has athermosetting or ultraviolet-setting property.
 10. The method of makinga semiconductor device as defined in claim 1 , wherein said gappreservation member has a property of absorbing stress between saidsemiconductor chip and said flexible substrate, and said gappreservation member adhering to said semiconductor chip and said facingsurface of said flexible substrate to form a stress absorption layer.11. The method of making a semiconductor device as defined in claim 10 ,wherein said gap preservation member has thermoplastic property, andsaid step of forming a stress absorption layer comprises a step Ofapplying heat and pressure to said gap preservation member.
 12. Themethod of making a semiconductor device as defined in claim 11 , whereinduring said step of applying pressure, a position at which pressure isapplied to said gap preservation member is gradually shifted, to performa sequence of local pressure applications.
 13. The method of making asemiconductor device as defined in claim 1 , wherein said gappreservation member is provided only on said surface of said flexiblesubstrate disposed facing said surface having said electrodes of saidsemiconductor chip.
 14. The method of making a semiconductor device asdefined in claim 13 , wherein said step of providing said gappreservation is included in a step of forming a wiring pattern that isprovided on said surface of said flexible substrate facing saidsemiconductor chip, and a plurality of protrusions are formed on saidwiring pattern by etching predetermined locations during said step offorming said wiring pattern.
 15. The method of making a semiconductordevice as defined in claim 14 , wherein through holes are formed in saidflexible substrate at positions corresponding to said protrusions, andsaid external electrodes are provided through said through holes on asurface of said flexible substrate opposite to said surface on whichsaid wiring pattern is provided.
 16. The method of making asemiconductor device as defined in claim 15 , further comprising a stepof painting an insulating resin onto at least positions of saidprotrusions facing said semiconductor chip, said protrusions acting assaid gap preservation member.
 17. A semiconductor device comprising: asemiconductor chip having electrodes; a flexible substrate disposed overand overlapping said semiconductor chip with a predetermined gaptherebetween, said flexible substrate having external electrodeformation portions within said overlapping region, said flexiblesubstrate having connection portions electrically connected to saidexternal electrode formation portions, said connection portionsconnected to said electrodes of said semiconductor chip; and a gappreservation member provided at a position which excludes a positioncorresponding to said external electrode formation portions, said gappreservation member preserving said gap.
 18. The semiconductor device asdefined in claim 17 , wherein an active region of said semiconductorchip is positioned within said overlapping region of said flexiblesubstrate.
 19. The semiconductor device as defined in claim 17 , furthercomprising a stress absorption layer positioned between saidsemiconductor chip and said flexible substrate.
 20. The semiconductordevice as defined in claim 19 , wherein said stress absorption layer isprovided in said position corresponding to said external electrodeformation portions.
 21. The semiconductor device as defined in claim 17, wherein at least part of a wiring pattern of said flexible substrateis used as said gap preservation member.
 22. The semiconductor device asdefined in claim 21 , wherein said wiring pattern has a plurality ofprotrusions, at least one of said protrusions is said gap preservationmember, and at least one of the rest of said protrusions is one of saidconnection portions to one of said electrodes of said semiconductorchip.
 23. The semiconductor device as defined in claim 22 , furthercomprising external electrodes formed on a side of said flexiblesubstrate, said side of said flexible substrate being opposite to a sidewhere said wiring pattern is formed, said external electrodes formedcorresponding to a position where said at least one of said protrusionsas said gap preservation member is formed.
 24. The semiconductor deviceas defined in claim 17 , wherein said gap preservation member is formedof resin and also acts as a stress absorption layer.
 25. Thesemiconductor device as defined in claim 24 , wherein said resin is athermoplastic resin.
 26. A circuit board comprising the semiconductordevice as defined in any one of claims 17 to 25 , wherein saidsemiconductor device is mounted and electrically connected through saidexternal electrode formation portions of said semiconductor device. 27.The circuit board as defined in claim 26 , further comprising connectingportions to said semiconductor device, wherein said semiconductor deviceis mounted thereon by a direct connection between said connectingportions and external electrodes formed on said external electrodeformation portions of said semiconductor device.
 28. A flexiblesubstrate comprising: a base portion; and a wiring pattern provided onone surface of said base portion, said wiring pattern having a pluralityof protrusions formed integrally thereon, said base portion havingthrough holes formed therein, each of said through holes correspondingto a position at which each of said plurality of protrusions areprovided.
 29. The flexible substrate as defined in claim 28 , whereinsaid protrusions form connection portions to electrodes of asemiconductor chip and a gap preservation member, and an insulatinglayer is provided on a surface of one of said protrusions as said gappreservation member.
 30. A flexible substrate comprising: connectionportions, said connection portions connected to electrodes of asemiconductor chip; and a gap preservation member made of resin, saidgap preservation member provided on a side where said connectionportions are provided, said gap preservation member provided at aposition that excludes said connection portions.
 31. The flexiblesubstrate as defined in claim 30 , wherein said gap preservation memberis made from a thermoplastic resin.